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Peracarida Look for this name in NCBI Wikipedia Animal Diversity Web
Wolfe et al. 2016
node minimum age |
Specimens are derived from the Francis Creek Shale Member of the Carbondale Formation, Mazon Creek, Illinois, of Westphalian D age (Baird et al., 1985; Shabica and Hay, 1997). The Westphalian D is equivalent to the latest Moscovian stage of the Pennsylvanian (Richards,2013). As the upper boundary of the Moscovian is 307.0 Ma± 0.1 Myr, this provides a minimum age of 306.9 Ma.
node maximum age |
A soft maximum age is obtained from the oldest mandibulate, Y. dianensis, which was recovered from the Yu'anshan Formation at Xiaotan section, Yongshan, Yunnan Province, attributed to the Eoredlichia–Wutingaspis Biozone (Zhang et al., 2007). Chinese Cambrian stratigraphy has been revised substantially and the Eoredlichia –Wutingaspis Biozone is no longer recognized (Peng, 2003, 2009). However, Eoredlichia is known to co-occur with Hupeidiscus, which is diagnostic of the Hupeidiscus-Sinodiscus Biozone, which is formally recognized as the second biozone of the Nangaoan Stage of the Qiandongian Series of the Cambrian of China (Peng and Babcock,2008). The Nangaoan is the proposed third stage of the Cambrian System for the International Geologic Timescale (Peng et al., 2012a).Thus, a soft maximum constraint can be established on the age of the lower boundary of the Nangaoan, which has been dated to 521 Ma (Peng et al., 2012a; Peng and Babcock, 2008).
|primary fossil used to date this node|
FMNH PE 16527
H. shermani was included in a morphological cladistic analysis by Wilson (2012). It occurred at the base of Phreatoicidea (Wilson, 2012), a position within the crown group of Isopoda and thus, crown Peracarida. Note that the assignment of our calibration fossil to crown Isopoda means that exclusion of Mysida from Peracarida (Jenner et al., 2009; Meland and Willassen, 2007; Spears et al., 2005) will not change the date assessed for Peracarida.
The linked fossil has no phylogentic references.
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